Mitochondrial DNA divergence in populations of the tapeworm Diphyllobothrium nihonkaiense and its phylogenetic relationship with Diphyllobothrium klebanovskii

Diphyllobothrium nihonkaiense [Y. Yamane, H. Kamo, G. Bylund, J.P. Wilkgren. Diphyllobothrium nihonkaiense sp. nov (Cestoda: Diphyllobothriidae)- revised identification of Japanese broad tapeworm. Shimane J Med Sci 1986;10:29-48.] and Diphyllobothrium klebanovskii [I.V. Muratov, P.S. Posokhov. Causative agent of human diphyllobothriasis - Diphyllobothrium klebanovskii sp. n. Parazitologiia. 1988;22:165-170.] are two major species of human diphyllobothriasis in Japan and Far East Russia, respectively, but their taxonomical relationship remains unclear. In this study, we analysed the DNA sequences of 16 clinical isolates of D. nihonkaiense from Japanese people, 3 isolates of D. klebanovskii from a bear in Kamchatka, and 4 clinical isolates of D. klebanovskii from native Udygeyci people in Russia, as well as 4 plerocercoids from Oncorhynchus spp. 18S rDNA and internal transcribed spacer 1 (ITS1) sequences from D. nihonkaiense and D. klebanovskii showed a high level of similarity, indicating synonymy of the two species. Analyses of mitochondrial DNA (mtDNA) sequence polymorphisms in the cox1 and nad3 genes of D. nihonkaiense (D. klebanovskii) revealed two deeply divergent lineages, A and B, with genetic distances (Kimura-2 parameter) of 0.018-0.022. Furthermore, the distinct monophyletic groupings of cox1 haplotypes corresponded to the distinct monophyletic groupings of nad3 haplotypes. The two lineages were neither distinguished by morphological features nor defined by the localities of the samples. These results suggest that the two morphologically cryptic lineages have diverged and coexisted over a long period of time.     

Basic pH-induced modification of excitation-energy dynamics in fucoxanthin chlorophyll a/c-binding proteins isolated from a pinguiophyte,Glossomastix chrysoplasta

Photosynthetic organisms have diversified light-harvesting complexes (LHCs) to collect solar energy efficiently, leading to an acquisition of their ecological niches. Herein we report on biochemical and spectroscopic characterizations of fucoxanthin chlorophyll a/c-binding protein (FCP) complexes isolated from a marine pinguiophyte Glossomastix chrysoplasta. The pinguiophyte FCP showed one subunit band in SDS-PAGE and one protein-complex band with a molecular weight at around 66 kDa in clear-native PAGE. By HPLC analysis, the FCP possesses chlorophylls a and c, fucoxanthin, and violaxanthin. To clarify excitation-energy-relaxation processes in the FCP, we measured time-resolved fluorescence spectra at 77 K of the FCP adapted to pH 5.0, 6.5, and 8.0. Fluorescence curves measured at pH 5.0 and 8.0 showed shorter lifetime components compared with those at pH 6.5. The rapid decay components at pH 5.0 and 8.0 are unveiled by fluorescence decay-associated (FDA) spectra; fluorescence decays occur in the 270 and 160-ps FDA spectra only at pH 5.0 and 8.0, respectively. In addition, energy-transfer pathways with time constants of tens of picoseconds are altered under the basic pH condition but not the acidic pH condition. These findings provide novel insights into pH-dependent energy-transfer and energy-quenching machinery in not only FCP family but also photosynthetic LHCs.     

Crystal Structures of Ethanolamine Ammonia-lyase Complexed with Coenzyme B12 Analogs and Substrates

N-terminal truncation of the Escherichia coli ethanolamine ammonia-lyase β-subunit does not affect the catalytic properties of the enzyme (Akita, K., Hieda, N., Baba, N., Kawaguchi, S., Sakamoto, H., Nakanishi, Y., Yamanishi, M., Mori, K., and Toraya, T. (2010) J. Biochem. 147, 83–93). The binary complex of the truncated enzyme with cyanocobalamin and the ternary complex with cyanocobalamin or adeninylpentylcobalamin and substrates were crystallized, and their x-ray structures were analyzed. The enzyme exists as a trimer of the (αβ)₂ dimer. The active site is in the (β/α)₈ barrel of the α-subunit; the β-subunit covers the lower part of the cobalamin that is bound in the interface of the α- and β-subunits. The structure complexed with adeninylpentylcobalamin revealed the presence of an adenine ring-binding pocket in the enzyme that accommodates the adenine moiety through a hydrogen bond network. The substrate is bound by six hydrogen bonds with active-site residues. Argα¹⁶⁰ contributes to substrate binding most likely by hydrogen bonding with the O1 atom. The modeling study implies that marked angular strains and tensile forces induced by tight enzyme-coenzyme interactions are responsible for breaking the coenzyme Co–C bond. The coenzyme adenosyl radical in the productive conformation was modeled by superimposing its adenine ring on the adenine ring-binding site followed by ribosyl rotation around the N-glycosidic bond. A major structural change upon substrate binding was not observed with this particular enzyme. Gluα²⁸⁷, one of the substrate-binding residues, has a direct contact with the ribose group of the modeled adenosylcobalamin, which may contribute to the substrate-induced additional labilization of the Co–C bond.     

Home range structure and inter-group competition for land of Japanese macaques in evergreen and deciduous forests

The per capita home range area of Japanese macaques,Macaca fuscata, is significantly smaller in evergreen forest than in deciduous forest, though a corresponding difference in food resource utilization patterns has never been described. The present study compared the home range utilization pattern of Japanese macaques living in two habitats: the Yakushima population inhabits an evergreen forest, while the Kinkazan population inhabits a deciduous forest. We found that in the Yakushima population, (1) food density was higher; (2) inter-feeding bout sites distance was shorter; (3) daily travel distance was shorter; (4) home range size was smaller; and (5) the unit value of the main home range was higher, than in the Kinkazan population. Yakushima groups utilized a small home range area intensively, compared to Kinkazan groups. We also found that a Yakushima group shared 24% of its main home range with neighboring groups, though a Kinkazan group shared only 10% with other groups. It is supposed that food distribution affects daily ranging pattern, and ultimately the social relationships between groups in Japanese macaques.     

Fluorometric estimation of surface potential change associated with chemotactic stimulation in Tetrahymena pyriformis

For the quantitative estimation of surface potential change in intact cells a method was devised with the use of fluorescent probes, 8-anilino-1-naphthalenesulfonate (ANS) and N-phenyl-1-naphthylamine (NPN). Estimated values in liposomes were compared with changes in the zeta potential determined from electrophoresis. Both values agreed within the experimental variation, showing the usefulness of the method. The method was also applied to Tetrahymena pyriformis, which exhibits chemotaxis to various chemical stimuli. The surface potential change was observed when the cell was stimulated not only by inorganic salts but also by electrically neutral, hydrophobic compounds. The surface potential started to change in accordance with the depolarization of the membrane potential, except for the case of K⁺. Changes in the surface potential of T. pyriformis in response to Ca²⁺ and K⁺ were compared with those in the membrane potential. The quantitative contribution of the surface potential to cell depolarization associated with chemoreception is discussed.     

Immunohistochemical Localization of Manserin,a Novel Neuropeptide Derived from Secretogranin II,in Rat Adrenal Gland,and its Upregulation by Physical Stress

We recently identified a novel 40-amino acid neuropeptide designated manserin from the rat brain (Yajima in NeuroReport 15: 1755–1759, 2004). Manserin is highly expressed in pituitary and hypothalamic nuclei, which suggests that it plays a role in the endocrine system. In this study, we employed immunohistochemical methods to investigate the presence of manserin in rat adrenal glands, as well as its regulation by physical stress. Immunohistochemical analysis using anti-manserin antibody showed that manserin is present in the rat adrenal medulla but not in the cortex. When the colocalization of manserin and phenylethanolamine N-methyltransferase (PNMT), an epinephrine-synthesizing enzyme, was examined, virtually all PNMT-positive cells expressed manserin. Interestingly, the immunoreactivity of manserin was significantly increased when the rats were exposed to water-immersion restraint stress. These results demonstrate for the first time that adrenal manserin, a novel neuropeptide, may have a potential physiological role under stress-inducing conditions.